1. Field of the Invention
This invention relates to a novel phenol-free photoresist stripping composition and method, particularly useful in the fabrication of integrated circuits. More particularly, it relates to such a stripping composition and method which is useful for both positive and negative photoresist, and which is free of compounds that have presented safety and environmental problems in prior art photoresist stripping compositions and methods.
2. Description of the Prior Art
In integrated circuit manufacturing, various compositions have been used for stripping organic photoresist polymers from silicon dioxide and other insulator surfaces, as well as metallized silicon dioxide or other insulator surfaces. The photoresist strippers currently in most general use, including 712D photoresist stripper available from the assignee of this application, J-100 photoresist stripper, available from Indust-Ri-Chem, and A-20, A-30 and A-40 photoresist stripper, available from Allied Chemical Corporation, are mixtures of certain organic sulfonic acids, phenol and chlorinated hydrocarbon solvents. A further description of the Allied Chemical compositions is contained in U.S. Pat. No. 4,165,295, which discloses the addition of fluoride ion to a stripping composition to help prevent attack on aluminum. A problem associated with the fluoride ion is that it will attack silicon dioxide.
As a result of safety and environmental problems associated with the chlorinated hydrocarbon solvents and phenol, it is desired to provide suitable replacements for these components of the compositions. Various photoresist stripper compositions have been offered to the semiconductor industry which do not contain phenol, but they have not proved as suitable in practice as the above compositions. Some of these substitute compositions are also acid-free, but those compositions are effective only on positive photoresist.
An effective replacement for the generally used above photoresist stripping compositions should meet the following criteria: The composition should be phenol and chlorinated hydrocarbon solvent-free, it should be water rinsable, non-corrosive to silicon, silicon dioxide, aluminum, aluminum silicon alloys, aluminum copper alloys, nickel chromium alloys and gold under normal operating conditions.
Thus, while the art of photoresist stripping compositions and methods is a well developed one, a need still remains for a suitable replacement stripping composition and method for the compositions and methods currently in general use in the semiconductor industry.